@article{doweneedhigherorderprobabilitiesandif,
  title = {Do We Need Higher-Order Probabilities and, If So, What Do They Mean?},
  author = {Judea Pearl},
  year = {2013},
  eprint = {1304.2716},
  archivePrefix = {arXiv},
  url = {http://arxiv.org/abs/1304.2716v1},
}